1. Field of the Invention
This invention relates to a storage cabinet, and more particularly, a storage cabinet for housing circuit boards which are susceptible to damage from static electricity or from rapid discharge of the components thereon after the boards are taken out of service.
2. Description of Prior Art
Heretofore it had been common to handle and store plug-in type circuit board modules in plastic barrier bags or plastic blocks such as "Styrofoam" which has been rendered conductive in order to preclude the modules from being damaged by static electricity in the ambient air or discharged from a person handling the module. Static electricity in the ambient surroundings could set up a sufficient voltage or potential differential between the surroundings and certain electrical components on the module e.g., integrated circuits, to cause substantial damage to the circuit contained on the board. Rapid discharge of components on a circuit board, after the board is removed from service, can also cause substantial damage to the circuitry. Since such circuit boards are used in various high technology applications, such as telephone switching and/or communications circuits, they are expensive, and the inadvertent discharge of any component on the board may lead to considerable repair expenses and/or considerable expenses in replacement of the entire board assembly.
Since the demand for telephone switching circuits may vary from peak periods to peak periods, for example, in summer communities where there is an influx of summer residents, some desirable storage facility must be provided for such plug-in circuit board modules between use. Such a facility must give ready access to the plug-in circuit board module when needed, but must provide a secure facility precluding rapid discharge of components and accidental exposure of the module to potentially damaging static electricity. Barrier bags and foamed polystyrene blocks, while suitable for handling and shipping individual modules, provide a clumsy and space inefficient storage mode for such modules.
Accordingly, this invention relates to a storage facility for plug-in circuit board modules when they are not in use, which is designed to conduct any static electricity away from the module to ground; yet, enables ready storage and access to the module in a storage cabinet wherein the modules can be slid in and out of the cabinet between adjustable height shelves, enabling the modules to be readily classified and identified.